1. Field of the Invention
The present invention relates to a multi-joint arm robot apparatus.
2. Discussion of the Background
Since circumstances in facilities such as nuclear reactor, fusion reactor and nuclear fuel reprocessing plants are harmful to human beings, work there is usually done by manipulators. The demand for a manipulator capable of more complicated movement has increased, and multi-joint arm robot apparatuses having a higher degree of freedom in movement have been developed to meet the demand.
Such multi-joint arm robot apparatus is disclosed in U.S. patent application Ser. No. 418,208, filed Sept. 15, 1982, U.S. Pat. No. 4,480,495, and Ser. No. 545,275, filed Oct. 25, 1983, both being assigned to the same assignee as this application. The multi-joint arm robot has, as roughly shown in FIG. 1, a plurality of unit arms 2 (2a, 2b, 2c . . . ) connected in tandem through joints 1 (1a, 1b, 1c . . . ). However, the movement of the multi-joint arm robot apparatus becomes extremely complicated, and complicated controls are needed to overcome obstacles in guiding the foremost end of the multi-joint arm to a target.
A rotation angle detector 5, obstacle detector 6, and the like are therefore provided in each of the joints 1 of the multi-joint arm robot, as shown in FIG. 1, and signals detected by these detectors 5 and 6 are applied to a control system to control the multi-joint arm movement.
Since the signals relating to rotation angle, rotation angle limit and obstacle detections are separately transmitted to the control system through signal transmission lines wired in the multi-joint arm, many signal transmission lines must be wired in each of the unit arms 2 so that the number of the signal lines in a unit arm increases as the unit arm is arranged nearer to the base end of the multi-joint arm. Therefore, a space wide enough to wire the signal lines is needed in the multi-joint arm. In addition, these many signal lines are tied in a bundle whose bending resistance increases accordingly, thereby requiring each of the joints to have a large driving force. Such a robot with a high degree of freedom in movement as described above will be large and complicated.